The full effects of the Paris Hilton sex tape's Internet arrival last month have yet to be calculated. How many office hours were lost to labyrinthine Googling? How much bandwidth was wasted on spurious files involving dancing monkeys, a '90s Hilton-look-alike porn clip or, in one ingenious example, a weirdo in a fake mustache and wig cooing into his webcam: "I'm Paris Hilton! I just had sex! I hope the meeeedia doesn't find out!"? And how many copies of the latest version of Windows Media Player had to be downloaded once the real thing was located?

For those who haven't managed to see the real movie online, or failed to read numerous reports of its contents, the under-three-minute clip was purportedly excerpted from a much longer tape made in 2001 when party-girl heiress Hilton, then 19, was dating Hollywood producer and Internet gambling mogul Rick Solomon, then 30. Shot in eerie green camcorder night vision, the video shows the couple grunting gleefully through several positions, and ends with a generously documented fellatio scene. Sometimes Solomon holds the camera, giving his perspective; at other times, the camera sits bedside, and the two glance over occasionally to see how they look in the LCD screen. Director-like, Solomon tells Hilton to reposition herself repeatedly, at one point facing her directly into the camera, "so you'll get to see what I get to see." Orwhether Solomon knew it or notso millions of others would. Although recent documents posted on muckraking website the Smoking Gun suggest Solomon had a hand in getting the complete tape to a potential distributor, he currently denies involvement in releasing it.

The Hilton tape is only the latest example in a long-flourishing underground trade in celebrity pornography, whose scope has increased dramatically with each innovation in motion picture technology. Even the Hilton fakes have many antecedents. As star-porn history shows, demand has always outstripped supply, creating a fantasy-driven environment filled with outright fakes, tantalizing come-ons that fail to deliver, mysterious artifacts of disputed provenance, and numerous curiosities that circulate due more to freak factor than any erotic frisson.

The distant seeds of celebrity porn took root in 19th-century literary erotica attributed to famous authors, such as the mock-epic Don Leon, claimed to have been penned by Lord Byron as a record of his notorious exploits, or the explicitly homosexual Victorian novel Teleny, long said to have been written by Oscar Wilde. After Hollywood invented the movie star in the early 20th century, Tijuana Bibles satisfied a new desire to see screen deities stripped bare. These crudely drawn comic-book leaflets depicted stars like Jean Harlow, Greta Garbo, and Clark Gable in various farcical trysts.

Hardcore porn films have existed at least since the teens, circulated through private clubs and wealthy collectors. Ancient Hollywood gossip has it that Joan Crawford acted in several early stag films, including some with lesbian scenes. But one of the earliest star-attributed films to circulate widely was a nameless one-reel nudie loop purporting to depict a young Marilyn Monroe, who would have shot it around 1948, prior to her posing nude for the inaugural issue of Playboy. In the film, a lone young woman does a striptease, rolls an apple across her chest, and then sips a soda. Later dubbed The Apple Knockers and the Coke, it was distributed to colleges and cinemas in the early '70s by Grove Films, packaged in a collection of vintage erotic shorts and experimental works like Carolee Schneemann's Fuses. Today, it's recognized that Apple Knockers and several other so-called Monroe porn films depict another early Playboy model named Arline Hunter.

One Monroe stag film remains in dispute, however. Also dated from 1948, this unnamed 16mm hardcore short shows a Monroe-ringer screwing a mustached man on a couch. According to a 1980 Penthouse cover story, a print was discovered that year by a Swedish photographer and subsequently publicized in adult magazines and tabloids worldwide. "Here, in grainy celluloid," Penthouse wrote next to copious frame-enlargements, "may well be the still unglamorized sex goddess the public never knew, before plastic surgeons, stylists, and designers transformed her into the mythical Marilyn Monroe. It's a thought to fire the imagination of every man who ever dreamed of her, a fantasy come to fruition." Another print of probably the same film garnered headlines in industry trades when it surfaced at a Spanish festival for film collectors in 1997. Those who argue the actress is Monroe point to declassified FBI files from 1965 detailing that Joe DiMaggio offered $25,000 for a print of a "French-type" movie depicting Monroe "in unnatural acts with an unknown male." Its authenticity seemed likely enough for Hollywood's Erotic Museum to purchase a print, now kept in its collection alongside artwork by Picasso and Tom of Finland.

During adult cinema's first boom in the '60s and '70s, similar celeb-porn urban legends took hold, many of which persist today. "Rumors of famous stars appearing in stags were impossible to squelch," blue-movie historian Jack Stevenson writes of this era, "because the public wanted so much to believe them." Playing to these desires, a number of star sex films were distributed through 8mm home catalogs and porn theaters, including silent loops allegedly depicting Jayne Mansfield and Barbra Streisand. The so-called Streisand film merely shows a young woman with a large nose having sex on camera; though available copies have become murky through generations of cheap dubbing, any resemblance seems far-fetched. Several hardcore gay films were made around this time starring Joe Dallesandro, according to film critic Dennis Dermody, who claims he has obtained video copies that clearly show Little Joe's telltale tattoo. Another gay stag is rumored to show B-actor Chuck Connors, of '50s TV series The Rifleman, although reports vary on the actual contents of the film.

But the true blossoming of celebrity skin flicks begins in the late 1970s, when the advent of home video recording engendered a new culture of underground tape-trading and pirated video, according to Hadrian Belove, one of the owners of the Los Angeles video store Cinefile, which specializes in rare titles, including real and imaginary star smut. "I don't think there was ever a time when people weren't tape trading," says Belove. "I remember Jack Valenti back in 1979 saying that taping off television was going to destroy the film industry. If there were people taping things, there's people trading things."

Sylvester Stallone in The Party at Kitty & Studs (1970) (photo: Anne Barry-Jester)

Like the image quality itself, the line between business and bootlegs was blurry. "It was such a free-for-all in the early '80s that most of those tapes we think of as legit were bootlegs," says Belove. "There was a hunger for stuff on video and there was no industry to police it at all, and so any serious bootlegger could just put it out. That includes horror, porn, all kinds of weird stuff like that." Some of the early celebrity porn titles were older films made before current stars were famous, like a 1970 Sylvester Stallone softcore film called

With home video came the home video camera, and thereby a new twist emerged: the samizdat-distributed celebrity home moviethe Paris Hilton tape's direct ancestor. The earliest instance is a lurid tape made in the late '70s by Jayne Kennedy and Leon Isaac Kennedy, known for their roles in blaxploitation titles and television. According to Don (who preferred not to give his last name) from Video Search of Miami, a longtime purveyor in celebrity sex videos, the Kennedys title was somehow released to the public by Leon after Jayne broke off their marriage, and remains a "big seller." Like many old traded tapes, the Kennedys' video is now distorted almost to abstraction, but the fisting scene no doubt helps it stay popular.

Video Search of Miami also distributes a half-hour tape called Chuck Berry's Home Movies, in which a man who sounds like the rock pioneer urinates on a woman in a tub while farting loudly, and the rock-legendary Go-Go's tape, which doesn't quite qualify as true celeb porn. "It's from the early '80s," says Don, "and the Go-Go's themselves aren't actually naked. It's sort of backstage stuff and you've got them getting fucked up and the guys around them getting naked." Another fame-culture twist is provided by a tape available at Cinefile as Steve Vai's Biggest Fan! Said to be a video love letter to the Whitesnake guitar god, it shows a young woman masturbating on camera for Vai, at one point performing tricks with a candle. The fan's obsession serves as stand-in for the absent star himself; in this way, it functions as the Heavy Metal Parking Lot of erotica.

But tape trading went even further mainstream in the next decade. "The Internet was the biggest explosion of all this, and it was simply from people being able to contact each other," remembers Belove, "because before this, you simply had mail order catalogs." Whereas trading had occurred within relatively small circles of collectors, and tapes took years to travel via word of mouth, "now if something gets out," says Belove, "the time it takes to spread is no time at all." This was illustrated dramatically by the last decade's string of celebrity sex-video scandals, stoked by the rise of competitive entertainment news and the burgeoning online porn industry. The Rob Lowe 1988 hotel tapes re-emerged via Internet tape traders in the early '90s, according to trader Mike Plante, editor of Cinemad magazine. Tonya Harding and Jeff Gillooly's so-called "Wedding Night Tape" and the much lauded Pamela Anderson-Tommy Lee tape both became so widely available that each party decided to release them officially. The latter also inspired a made-for-release hardcore video starring fellow Mötley Crüe member Vince Neil and a professional porn actress, Janine.

As broadband has spread, nearly all the videos mentioned aboveplus others like Simon Rex's gay jerk-off video, Pamela's unreleased sex tapes with Poison's Bret Michaels, or Hogan's Heroes star Bob Crane's films (made infamous by Paul Schrader's Auto Focus)have gained new life online, sold as files on countless porn sites or downloaded off Kazaa as easily as the latest 50 Cent MP3. But just as in the day of the Tijuana Bibles, demand exceeds supply, and numerous purported videos of R. Kelly or various cast members of Star Trek: The Next Generation turn out to be mere porn-industry look-alikes or Celebrity Sleuth-style split-second clips from obscure nonsex roles. "In almost all of these," says Plante, "you hear about it, and it's described a certain way, and it sounds amazing, and it always fails to live up to expectations."

Now, the ease and reach of peer-to-peer networks mean that fakes and halfhearted bits of reality circulate endlessly, despite their unsatisfying qualities. But transcending mere prurience, new technologies increasingly feed and foster voracious desires to look ever closeras far as the cameras will go. In this regard, it's not coincidental that the Hilton tape was shot with the same night vision as recent Iraq battle footage, or that it spread virally, like the ghastly Daniel Pearl video. The hunger for forbidden knowledge, whether of sex or death, remains constant.